search for: _with_success

I've already posted a patch (https://reviews.llvm.org/D41791) to do this, but here's a bit of a background. When the operands of an ISD::ATOMIC_CMP_SWAP{_WITH_SUCCESS} are legalized by promoting to a larger type, they're extended without specifying whether it's a sign or zero extension. However, an analogous node (SETCC) is legalized by zero-extending when the comparison code is for an equality comparison. The current legalization scheme leads to a bug...